The need for rapid, inexpensive and effective tests of large numbers of biological specimens for materials of clinical significance, such as steroids, hormones and drugs, has accelerated the evolution of new techniques and apparatus to supplant or improve upon the otherwise effective solvent-extraction thin-layer chromatography techniques of past years. Typically, improved results are achieved in one category, such as cost, by sacrificing another, such as scope of the analysis in terms of the number of the materials detected in any one analysis. Disposable cartridges using special adsorption resins and, more recently, the simultaneous testing of multiple pre-processed samples, have been evolved but none has freed the art of the need for more rapid, less expensive, and less labor-intensive procedures.
The present invention has for its objects to provide a system for automatically extracting compounds of clinical significance from biological samples and, further, for providing for the simultaneous extraction of these compounds and subsequent elution from a large number of biological specimens. Also provided are multi-channel valves and metering means for simultaneously controlling fluid flow, both liquid and gas, into and out of each channel from common control impulses derived from a programmed source.